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authorhongbotian <hongbo.tianhongbo@huawei.com>2015-11-30 01:35:09 -0500
committerhongbotian <hongbo.tianhongbo@huawei.com>2015-11-30 01:36:35 -0500
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parent68e74fd78b2485e5914ce34a5b30f4485029e021 (diff)
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JIRA: BOTTLENECK-10 Change-Id: I67eae31de6dc824097dfa56ab454ba36fdd23a2c Signed-off-by: hongbotian <hongbo.tianhongbo@huawei.com>
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+<?xml version="1.0" encoding="ISO-8859-1"?>
+<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
+<html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ This file is generated from xml source: DO NOT EDIT
+ XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
+ -->
+<title>Apache Tutorial: Dynamic Content with CGI - Apache HTTP Server</title>
+<link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
+<link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
+<link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
+<link href="../images/favicon.ico" rel="shortcut icon" /></head>
+<body id="manual-page"><div id="page-header">
+<p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
+<p class="apache">Apache HTTP Server Version 2.0</p>
+<img alt="" src="../images/feather.gif" /></div>
+<div class="up"><a href="./"><img title="&lt;-" alt="&lt;-" src="../images/left.gif" /></a></div>
+<div id="path">
+<a href="http://www.apache.org/">Apache</a> &gt; <a href="http://httpd.apache.org/">HTTP Server</a> &gt; <a href="http://httpd.apache.org/docs/">Documentation</a> &gt; <a href="../">Version 2.0</a> &gt; <a href="./">How-To / Tutorials</a></div><div id="page-content"><div id="preamble"><h1>Apache Tutorial: Dynamic Content with CGI</h1>
+<div class="toplang">
+<p><span>Available Languages: </span><a href="../en/howto/cgi.html" title="English">&nbsp;en&nbsp;</a> |
+<a href="../ja/howto/cgi.html" hreflang="ja" rel="alternate" title="Japanese">&nbsp;ja&nbsp;</a> |
+<a href="../ko/howto/cgi.html" hreflang="ko" rel="alternate" title="Korean">&nbsp;ko&nbsp;</a></p>
+</div>
+</div>
+<div id="quickview"><ul id="toc"><li><img alt="" src="../images/down.gif" /> <a href="#intro">Introduction</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#configuring">Configuring Apache to permit CGI</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#writing">Writing a CGI program</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#troubleshoot">But it's still not working!</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#behindscenes">What's going on behind the scenes?</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#libraries">CGI modules/libraries</a></li>
+<li><img alt="" src="../images/down.gif" /> <a href="#moreinfo">For more information</a></li>
+</ul></div>
+<div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="intro" id="intro">Introduction</a></h2>
+
+
+ <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="../mod/mod_alias.html">mod_alias</a></code></li><li><code class="module"><a href="../mod/mod_cgi.html">mod_cgi</a></code></li></ul></td><td><ul><li><code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code></li><li><code class="directive"><a href="../mod/core.html#options">Options</a></code></li><li><code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code></li></ul></td></tr></table>
+
+ <p>The CGI (Common Gateway Interface) defines a way for a web
+ server to interact with external content-generating programs,
+ which are often referred to as CGI programs or CGI scripts. It
+ is the simplest, and most common, way to put dynamic content on
+ your web site. This document will be an introduction to setting
+ up CGI on your Apache web server, and getting started writing
+ CGI programs.</p>
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="configuring" id="configuring">Configuring Apache to permit CGI</a></h2>
+
+
+ <p>In order to get your CGI programs to work properly, you'll
+ need to have Apache configured to permit CGI execution. There
+ are several ways to do this.</p>
+
+ <h3><a name="scriptalias" id="scriptalias">ScriptAlias</a></h3>
+
+
+ <p>The
+ <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
+
+ directive tells Apache that a particular directory is set
+ aside for CGI programs. Apache will assume that every file in
+ this directory is a CGI program, and will attempt to execute
+ it, when that particular resource is requested by a
+ client.</p>
+
+ <p>The <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
+ directive looks like:</p>
+
+ <div class="example"><p><code>
+ ScriptAlias /cgi-bin/ /usr/local/apache2/cgi-bin/
+ </code></p></div>
+
+ <p>The example shown is from your default <code>httpd.conf</code>
+ configuration file, if you installed Apache in the default
+ location. The <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>
+ directive is much like the <code class="directive"><a href="../mod/mod_alias.html#alias">Alias</a></code> directive, which defines a URL prefix that
+ is to mapped to a particular directory. <code class="directive">Alias</code>
+ and <code class="directive">ScriptAlias</code> are usually used for
+ directories that are outside of the <code class="directive"><a href="../mod/core.html#documentroot">DocumentRoot</a></code> directory. The difference between
+ <code class="directive">Alias</code> and <code class="directive">ScriptAlias</code>
+ is that <code class="directive">ScriptAlias</code> has the added meaning
+ that everything under that URL prefix will be considered a CGI
+ program. So, the example above tells Apache that any request for a
+ resource beginning with <code>/cgi-bin/</code> should be served from
+ the directory <code>/usr/local/apache2/cgi-bin/</code>, and should be
+ treated as a CGI program.</p>
+
+ <p>For example, if the URL
+ <code>http://www.example.com/cgi-bin/test.pl</code>
+ is requested, Apache will attempt to execute the file
+ <code>/usr/local/apache2/cgi-bin/test.pl</code>
+ and return the output. Of course, the file will have to
+ exist, and be executable, and return output in a particular
+ way, or Apache will return an error message.</p>
+
+
+ <h3><a name="nonscriptalias" id="nonscriptalias">CGI outside of ScriptAlias directories</a></h3>
+
+
+ <p>CGI programs are often restricted to <code class="directive"><a href="../mod/mod_alias.html#scriptalias">ScriptAlias</a></code>'ed directories for security reasons.
+ In this way, administrators can tightly control who is allowed to
+ use CGI programs. However, if the proper security precautions are
+ taken, there is no reason why CGI programs cannot be run from
+ arbitrary directories. For example, you may wish to let users
+ have web content in their home directories with the
+ <code class="directive"><a href="../mod/mod_userdir.html#userdir">UserDir</a></code> directive.
+ If they want to have their own CGI programs, but don't have access to
+ the main <code>cgi-bin</code> directory, they will need to be able to
+ run CGI programs elsewhere.</p>
+
+ <p>There are two steps to allowing CGI execution in an arbitrary
+ directory. First, the <code>cgi-script</code> handler must be
+ activated using the <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> or <code class="directive"><a href="../mod/core.html#sethandler">SetHandler</a></code> directive. Second,
+ <code>ExecCGI</code> must be specified in the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive.</p>
+
+
+ <h3><a name="options" id="options">Explicitly using Options to permit CGI execution</a></h3>
+
+
+ <p>You could explicitly use the <code class="directive"><a href="../mod/core.html#options">Options</a></code> directive, inside your main server configuration
+ file, to specify that CGI execution was permitted in a particular
+ directory:</p>
+
+ <div class="example"><p><code>
+ &lt;Directory /usr/local/apache2/htdocs/somedir&gt;<br />
+ <span class="indent">
+ Options +ExecCGI<br />
+ </span>
+ &lt;/Directory&gt;
+ </code></p></div>
+
+ <p>The above directive tells Apache to permit the execution
+ of CGI files. You will also need to tell the server what
+ files are CGI files. The following <code class="directive"><a href="../mod/mod_mime.html#addhandler">AddHandler</a></code> directive tells the server to treat all
+ files with the <code>cgi</code> or <code>pl</code> extension as CGI
+ programs:</p>
+
+ <div class="example"><p><code>
+ AddHandler cgi-script .cgi .pl
+ </code></p></div>
+
+
+ <h3><a name="htaccess" id="htaccess">.htaccess files</a></h3>
+
+
+ <p>The <a href="htaccess.html"><code>.htaccess</code> tutorial</a>
+ shows how to activate CGI programs if you do not have
+ access to <code>httpd.conf</code>.</p>
+
+
+ <h3><a name="userdir" id="userdir">User Directories</a></h3>
+
+
+ <p>To allow CGI program execution for any file ending in
+ <code>.cgi</code> in users' directories, you can use the
+ following configuration.</p>
+
+ <div class="example"><p><code>
+ &lt;Directory /home/*/public_html&gt;<br />
+ <span class="indent">
+ Options +ExecCGI<br />
+ AddHandler cgi-script .cgi<br />
+ </span>
+ &lt;/Directory&gt;
+ </code></p></div>
+
+ <p>If you wish designate a <code>cgi-bin</code> subdirectory of
+ a user's directory where everything will be treated as a CGI
+ program, you can use the following.</p>
+
+ <div class="example"><p><code>
+ &lt;Directory /home/*/public_html/cgi-bin&gt;<br />
+ <span class="indent">
+ Options ExecCGI<br />
+ SetHandler cgi-script<br />
+ </span>
+ &lt;/Directory&gt;
+ </code></p></div>
+
+
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="writing" id="writing">Writing a CGI program</a></h2>
+
+
+ <p>There are two main differences between ``regular''
+ programming, and CGI programming.</p>
+
+ <p>First, all output from your CGI program must be preceded by
+ a MIME-type header. This is HTTP header that tells the client
+ what sort of content it is receiving. Most of the time, this
+ will look like:</p>
+
+ <div class="example"><p><code>
+ Content-type: text/html
+ </code></p></div>
+
+ <p>Secondly, your output needs to be in HTML, or some other
+ format that a browser will be able to display. Most of the
+ time, this will be HTML, but occasionally you might write a CGI
+ program that outputs a gif image, or other non-HTML
+ content.</p>
+
+ <p>Apart from those two things, writing a CGI program will look
+ a lot like any other program that you might write.</p>
+
+ <h3><a name="firstcgi" id="firstcgi">Your first CGI program</a></h3>
+
+
+ <p>The following is an example CGI program that prints one
+ line to your browser. Type in the following, save it to a
+ file called <code>first.pl</code>, and put it in your
+ <code>cgi-bin</code> directory.</p>
+
+ <div class="example"><p><code>
+ #!/usr/bin/perl<br />
+ print "Content-type: text/html\n\n";<br />
+ print "Hello, World.";
+ </code></p></div>
+
+ <p>Even if you are not familiar with Perl, you should be able
+ to see what is happening here. The first line tells Apache
+ (or whatever shell you happen to be running under) that this
+ program can be executed by feeding the file to the
+ interpreter found at the location <code>/usr/bin/perl</code>.
+ The second line prints the content-type declaration we
+ talked about, followed by two carriage-return newline pairs.
+ This puts a blank line after the header, to indicate the end
+ of the HTTP headers, and the beginning of the body. The third
+ line prints the string "Hello, World.". And that's the end
+ of it.</p>
+
+ <p>If you open your favorite browser and tell it to get the
+ address</p>
+
+ <div class="example"><p><code>
+ http://www.example.com/cgi-bin/first.pl
+ </code></p></div>
+
+ <p>or wherever you put your file, you will see the one line
+ <code>Hello, World.</code> appear in your browser window.
+ It's not very exciting, but once you get that working, you'll
+ have a good chance of getting just about anything working.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="troubleshoot" id="troubleshoot">But it's still not working!</a></h2>
+
+
+ <p>There are four basic things that you may see in your browser
+ when you try to access your CGI program from the web:</p>
+
+ <dl>
+ <dt>The output of your CGI program</dt>
+ <dd>Great! That means everything worked fine. If the output is correct,
+ but the browser is not processing it correctly, make sure you have the
+ correct <code>Content-Type</code> set in your CGI program.</dd>
+
+ <dt>The source code of your CGI program or a "POST Method Not
+ Allowed" message</dt>
+ <dd>That means that you have not properly configured Apache
+ to process your CGI program. Reread the section on
+ <a href="#configuring">configuring
+ Apache</a> and try to find what you missed.</dd>
+
+ <dt>A message starting with "Forbidden"</dt>
+ <dd>That means that there is a permissions problem. Check the
+ <a href="#errorlogs">Apache error log</a> and the section below on
+ <a href="#permissions">file permissions</a>.</dd>
+
+ <dt>A message saying "Internal Server Error"</dt>
+ <dd>If you check the
+ <a href="#errorlogs">Apache error log</a>, you will probably
+ find that it says "Premature end of
+ script headers", possibly along with an error message
+ generated by your CGI program. In this case, you will want to
+ check each of the below sections to see what might be
+ preventing your CGI program from emitting the proper HTTP
+ headers.</dd>
+ </dl>
+
+ <h3><a name="permissions" id="permissions">File permissions</a></h3>
+
+
+ <p>Remember that the server does not run as you. That is,
+ when the server starts up, it is running with the permissions
+ of an unprivileged user - usually <code>nobody</code>, or
+ <code>www</code> - and so it will need extra permissions to
+ execute files that are owned by you. Usually, the way to give
+ a file sufficient permissions to be executed by <code>nobody</code>
+ is to give everyone execute permission on the file:</p>
+
+ <div class="example"><p><code>
+ chmod a+x first.pl
+ </code></p></div>
+
+ <p>Also, if your program reads from, or writes to, any other
+ files, those files will need to have the correct permissions
+ to permit this.</p>
+
+
+
+ <h3><a name="pathinformation" id="pathinformation">Path information and environment</a></h3>
+
+
+ <p>When you run a program from your command line, you have
+ certain information that is passed to the shell without you
+ thinking about it. For example, you have a <code>PATH</code>,
+ which tells the shell where it can look for files that you
+ reference.</p>
+
+ <p>When a program runs through the web server as a CGI program,
+ it may not have the same <code>PATH</code>. Any programs that you
+ invoke in your CGI program (like <code>sendmail</code>, for
+ example) will need to be specified by a full path, so that the
+ shell can find them when it attempts to execute your CGI
+ program.</p>
+
+ <p>A common manifestation of this is the path to the script
+ interpreter (often <code>perl</code>) indicated in the first
+ line of your CGI program, which will look something like:</p>
+
+ <div class="example"><p><code>
+ #!/usr/bin/perl
+ </code></p></div>
+
+ <p>Make sure that this is in fact the path to the
+ interpreter.</p>
+
+ <p>In addition, if your CGI program depends on other <a href="#env">environment variables</a>, you will need to
+ assure that those variables are passed by Apache.</p>
+
+
+
+ <h3><a name="syntaxerrors" id="syntaxerrors">Program errors</a></h3>
+
+
+ <p>Most of the time when a CGI program fails, it's because of
+ a problem with the program itself. This is particularly true
+ once you get the hang of this CGI stuff, and no longer make
+ the above two mistakes. The first thing to do is to make
+ sure that your program runs from the command line before
+ testing it via the web server. For example, try:</p>
+
+ <div class="example"><p><code>
+ cd /usr/local/apache2/cgi-bin<br />
+ ./first.pl
+ </code></p></div>
+
+ <p>(Do not call the <code>perl</code> interpreter. The shell
+ and Apache should find the interpreter using the <a href="#pathinformation">path information</a> on the first line of
+ the script.)</p>
+
+ <p>The first thing you see written by your program should be
+ a set of HTTP headers, including the <code>Content-Type</code>,
+ followed by a blank line. If you see anything else, Apache will
+ return the <code>Premature end of script headers</code> error if
+ you try to run it through the server. See <a href="#writing">Writing a CGI program</a> above for more
+ details.</p>
+
+
+ <h3><a name="errorlogs" id="errorlogs">Error logs</a></h3>
+
+
+ <p>The error logs are your friend. Anything that goes wrong
+ generates message in the error log. You should always look
+ there first. If the place where you are hosting your web site
+ does not permit you access to the error log, you should
+ probably host your site somewhere else. Learn to read the
+ error logs, and you'll find that almost all of your problems
+ are quickly identified, and quickly solved.</p>
+
+
+ <h3><a name="suexec" id="suexec">Suexec</a></h3>
+
+
+ <p>The <a href="../suexec.html">suexec</a> support program
+ allows CGI programs to be run under different user permissions,
+ depending on which virtual host or user home directory they are
+ located in. Suexec has very strict permission checking, and any
+ failure in that checking will result in your CGI programs
+ failing with <code>Premature end of script headers</code>.</p>
+
+ <p>To check if you are using suexec, run <code>apachectl
+ -V</code> and check for the location of <code>SUEXEC_BIN</code>.
+ If Apache finds an <code class="program"><a href="../programs/suexec.html">suexec</a></code> binary there on startup,
+ suexec will be activated.</p>
+
+ <p>Unless you fully understand suexec, you should not be using it.
+ To disable suexec, simply remove (or rename) the <code class="program"><a href="../programs/suexec.html">suexec</a></code>
+ binary pointed to by <code>SUEXEC_BIN</code> and then restart the
+ server. If, after reading about <a href="../suexec.html">suexec</a>,
+ you still wish to use it, then run <code>suexec -V</code> to find
+ the location of the suexec log file, and use that log file to
+ find what policy you are violating.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="behindscenes" id="behindscenes">What's going on behind the scenes?</a></h2>
+
+
+ <p>As you become more advanced in CGI programming, it will
+ become useful to understand more about what's happening behind
+ the scenes. Specifically, how the browser and server
+ communicate with one another. Because although it's all very
+ well to write a program that prints "Hello, World.", it's not
+ particularly useful.</p>
+
+ <h3><a name="env" id="env">Environment variables</a></h3>
+
+
+ <p>Environment variables are values that float around you as
+ you use your computer. They are useful things like your path
+ (where the computer searches for the actual file
+ implementing a command when you type it), your username, your
+ terminal type, and so on. For a full list of your normal,
+ every day environment variables, type
+ <code>env</code> at a command prompt.</p>
+
+ <p>During the CGI transaction, the server and the browser
+ also set environment variables, so that they can communicate
+ with one another. These are things like the browser type
+ (Netscape, IE, Lynx), the server type (Apache, IIS, WebSite),
+ the name of the CGI program that is being run, and so on.</p>
+
+ <p>These variables are available to the CGI programmer, and
+ are half of the story of the client-server communication. The
+ complete list of required variables is at
+ <a href="http://hoohoo.ncsa.uiuc.edu/cgi/env.html">http://hoohoo.ncsa.uiuc.edu/cgi/env.html</a>.</p>
+
+ <p>This simple Perl CGI program will display all of the
+ environment variables that are being passed around. Two
+ similar programs are included in the
+ <code>cgi-bin</code>
+
+ directory of the Apache distribution. Note that some
+ variables are required, while others are optional, so you may
+ see some variables listed that were not in the official list.
+ In addition, Apache provides many different ways for you to
+ <a href="../env.html">add your own environment variables</a>
+ to the basic ones provided by default.</p>
+
+ <div class="example"><p><code>
+ #!/usr/bin/perl<br />
+ print "Content-type: text/html\n\n";<br />
+ foreach $key (keys %ENV) {<br />
+ <span class="indent">
+ print "$key --&gt; $ENV{$key}&lt;br&gt;";<br />
+ </span>
+ }
+ </code></p></div>
+
+
+ <h3><a name="stdin" id="stdin">STDIN and STDOUT</a></h3>
+
+
+ <p>Other communication between the server and the client
+ happens over standard input (<code>STDIN</code>) and standard
+ output (<code>STDOUT</code>). In normal everyday context,
+ <code>STDIN</code> means the keyboard, or a file that a
+ program is given to act on, and <code>STDOUT</code>
+ usually means the console or screen.</p>
+
+ <p>When you <code>POST</code> a web form to a CGI program,
+ the data in that form is bundled up into a special format
+ and gets delivered to your CGI program over <code>STDIN</code>.
+ The program then can process that data as though it was
+ coming in from the keyboard, or from a file</p>
+
+ <p>The "special format" is very simple. A field name and
+ its value are joined together with an equals (=) sign, and
+ pairs of values are joined together with an ampersand
+ (&amp;). Inconvenient characters like spaces, ampersands, and
+ equals signs, are converted into their hex equivalent so that
+ they don't gum up the works. The whole data string might look
+ something like:</p>
+
+ <div class="example"><p><code>
+ name=Rich%20Bowen&amp;city=Lexington&amp;state=KY&amp;sidekick=Squirrel%20Monkey
+ </code></p></div>
+
+ <p>You'll sometimes also see this type of string appended to
+ a URL. When that is done, the server puts that string
+ into the environment variable called
+ <code>QUERY_STRING</code>. That's called a <code>GET</code>
+ request. Your HTML form specifies whether a <code>GET</code>
+ or a <code>POST</code> is used to deliver the data, by setting the
+ <code>METHOD</code> attribute in the <code>FORM</code> tag.</p>
+
+ <p>Your program is then responsible for splitting that string
+ up into useful information. Fortunately, there are libraries
+ and modules available to help you process this data, as well
+ as handle other of the aspects of your CGI program.</p>
+
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="libraries" id="libraries">CGI modules/libraries</a></h2>
+
+
+ <p>When you write CGI programs, you should consider using a
+ code library, or module, to do most of the grunt work for you.
+ This leads to fewer errors, and faster development.</p>
+
+ <p>If you're writing CGI programs in Perl, modules are
+ available on <a href="http://www.cpan.org/">CPAN</a>. The most
+ popular module for this purpose is <code>CGI.pm</code>. You might
+ also consider <code>CGI::Lite</code>, which implements a minimal
+ set of functionality, which is all you need in most programs.</p>
+
+ <p>If you're writing CGI programs in C, there are a variety of
+ options. One of these is the <code>CGIC</code> library, from
+ <a href="http://www.boutell.com/cgic/">http://www.boutell.com/cgic/</a>.</p>
+ </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
+<div class="section">
+<h2><a name="moreinfo" id="moreinfo">For more information</a></h2>
+
+
+ <p>There are a large number of CGI resources on the web. You
+ can discuss CGI problems with other users on the Usenet group
+ <a href="news:comp.infosystems.www.authoring.cgi">comp.infosystems.www.authoring.cgi</a>. And the -servers mailing
+ list from the HTML Writers Guild is a great source of answers
+ to your questions. You can find out more at
+ <a href="http://www.hwg.org/lists/hwg-servers/">http://www.hwg.org/lists/hwg-servers/</a>.</p>
+
+ <p>And, of course, you should probably read the CGI
+ specification, which has all the details on the operation of
+ CGI programs. You can find the original version at the
+ <a href="http://hoohoo.ncsa.uiuc.edu/cgi/interface.html">NCSA</a> and there is an updated draft at the
+ <a href="http://web.golux.com/coar/cgi/">Common Gateway
+ Interface RFC project</a>.</p>
+
+ <p>When you post a question about a CGI problem that you're
+ having, whether to a mailing list, or to a newsgroup, make sure
+ you provide enough information about what happened, what you
+ expected to happen, and how what actually happened was
+ different, what server you're running, what language your CGI
+ program was in, and, if possible, the offending code. This will
+ make finding your problem much simpler.</p>
+
+ <p>Note that questions about CGI problems should <strong>never</strong>
+ be posted to the Apache bug database unless you are sure you
+ have found a problem in the Apache source code.</p>
+ </div></div>
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